I think Haste could overtake mastery for Arms if they double it. Crit will probably be brought down a bit, as we'll be using Overpower more and it has a native 60% crit chance anyway, and the enrage effect for Arms, while good, is less important than Fury's enrage effect.

Also, I can see Expertise losing value... Wouldn't be surprised to see some weird results like Hit cap > Haste > Mastery > Crit > Expertise for stat priority, due to how often we'll be using Overpower.

I think Haste could overtake mastery for Arms if they double it. Crit will probably be brought down a bit, as we'll be using Overpower more and it has a native 60% crit chance anyway, and the enrage effect for Arms, while good, is less important than Fury's enrage effect.

Also, I can see Expertise losing value... Wouldn't be surprised to see some weird results like Hit cap > Haste > Mastery > Crit > Expertise for stat priority, due to how often we'll be using Overpower.

Blizzard said they would make haste better, but no way it would overtake a stat like Crit since how warrior scales so bad with haste. The difference between haste and crit currently is like the difference between the sun and the moon. Maybe Haste in 5.2 will come close to Mastery.

It will have a PPM limit just like everything else, haste will remain bottom tier, just with less of a huge gap.

Not sure if you're trying to say that haste will have no effect on the proc rate of the two piece, but if so, that's not correct. The real ppm system does scale with haste, so we will certainly see higher than base ppm.

It likely won't change stat priorities for fury but will certainly bring haste up a fair amount. It isn't completely beyond the realm of possibility that haste and mastery will be very close to each other if they go through with doubling the effect per rating of haste, and as enrage uptime gets higher both will gain in value relative to crit, though both will remain significantly behind in the next tier I suspect.

With my current Haste value ( 4.56% ) i found that:
for fury 9.9% uptime
for arms 24% uptime
for def 16.0% uptime
If we consider that the 2p T15 can proc from both weapon as fury it will change the PPM value to 2*0.6
It will give a 18.8% uptime for fury

Let's say that i double my haste (like i could be the case in t15)
i got those result:
for fury 10.4% uptime (or 19.6% if both weapon can proc)
for arms 25.2% uptime
for def 16.6% uptime

I think Haste could overtake mastery for Arms if they double it. Crit will probably be brought down a bit, as we'll be using Overpower more and it has a native 60% crit chance anyway, and the enrage effect for Arms, while good, is less important than Fury's enrage effect.

Also, I can see Expertise losing value... Wouldn't be surprised to see some weird results like Hit cap > Haste > Mastery > Crit > Expertise for stat priority, due to how often we'll be using Overpower.

Crit is always going to be one of our priorities. At best Haste will surpass Mastery, but that's it. And with the possible rage cost addition to Overpower, I wouldn't count on it being your bread and butter for long. Arms will be in a sore spot (more so than it already is for PvE) in 5.2 if the rage cost actually gets implemented.

Imho if the current MS=2xOP + 2 set tier bonus goes in, I'm sure Strength will just surpass other stats way more than currently, since it's the only thing that would scale OP's damage the most. Even now for arms Str vs. 2xCrit value is very close (for me Arms simmed str is ~2.5 while crit ~1.5), so this would mean that if crit loses a bit of its value, you would start to gem STR instead, and still reforge to crit/take all the crit gear you can. If only they would buff OP's damage by 10-15% it wouldn't be that bad, but currently it's a free weak attack with nerfed GCD, that really doesn't scale from anything else than attack power.

Mortal Strike, Colossus Smash, Execute, Mastery swings and Slam obviously still benefit from Crit, so it still would be the best offstat, but since Execute and Slam are getting most of their uptime within Recklessness and crit banner by looking the next tier bonuses, it would just pull STR way ahead overall.

... And then you would be thinking "Do I really have to gem to STR to be optimal?" and moment later completely switch to fury if it's just about PvE.

Imho if the current MS=2xOP + 2 set tier bonus goes in, I'm sure Strength will just surpass other stats way more than currently, since it's the only thing that would scale OP's damage the most. Even now for arms Str vs. 2xCrit value is very close (for me Arms simmed str is ~2.5 while crit ~1.5), so this would mean that if crit loses a bit of its value, you would start to gem STR instead, and still reforge to crit/take all the crit gear you can. If only they would buff OP's damage by 10-15% it wouldn't be that bad, but currently it's a free weak attack with nerfed GCD, that really doesn't scale from anything else than attack power.

Mortal Strike, Colossus Smash, Execute, Mastery swings and Slam obviously still benefit from Crit, so it still would be the best offstat, but since Execute and Slam are getting most of their uptime within Recklessness and crit banner by looking the next tier bonuses, it would just pull STR way ahead overall.

... And then you would be thinking "Do I really have to gem to STR to be optimal?" and moment later completely switch to fury if it's just about PvE.

But Warriors are already swimming 25+% crit with buffs and OP's crit chance in raid is around 85-90% atm! Just saying, that if the next gear includes a lot more crit on gear (depending on the ilvl inflation again) it's going to get less useful to actually gem on crit and see any direct bonus from it past that point. Now OP's overall damage done is less than 15%, but on PTR the total value runs closer to 25-30%. Even if the value of crit on my character would drop from 1.5 to 1.275 due to OP uptime and free enrage procs, it would make crit and str at least equal to gem for already.

We will see how it works out, but I think it's one possible outcome... I hope not though

But Warriors are already swimming 25+% crit with buffs and OP's crit chance in raid is around 85-90% atm! Just saying, that if the next gear includes a lot more crit on gear (depending on the ilvl inflation again) it's going to get less useful to actually gem on crit and see any direct bonus from it past that point. Now OP's overall damage done is less than 15%, but on PTR the total value runs closer to 25-30%. Even if the value of crit on my character would drop from 1.5 to 1.275 due to OP uptime and free enrage procs, it would make crit and str at least equal to gem for already.

We will see how it works out, but I think it's one possible outcome... I hope not though

Question still remains if arms dps can catch up with fury. Wild strikes will become free when procced which saves you 30 rage to do other things with.

I upgraded my eExceel sheets to estimate the gain we could get from the 2pt15 dps as SMF fury warior.
For the simulation i used the current gear value i have on my warrior.

i find this result: the 2p T15 is a 86 dps upgrade over the 2p T14
It show that 2p T15 is just as good as 2p T14 is currently. But the T15 will have an higher iLvL, which mean more overall stats which mean more overall dps gain.

I did try to "double my haste" to see what will happen.
After that the 2p T14 appears as a 273 dps increase. So the "double haste effect" seems like a 200 dps increase (concerning the 2p T15)